The synthesis, distribution, and anti-hepatic cancer activity of YSL Original Research Article

YSL was prepared stepwise from C terminal to N terminal with the side chain un-protective amino acids, Boc-Leu-OMe, Boc-Ser-OH, and Boc-Tyr-OH, as the starting materials in 39.5% total yield (31.2 g/per batch). With the side chain un-protective Boc-(3,5-dibromo)-Tyr-OH and HCl·Ser-Leu-OMe as the starting materials (3,5-3H-Tyr)-Ser-Leu-OH was obtained in 29% yield. The determination of radioactive quantity in the urine and feces indicated that even after the administration for 130 h only 8.4% (5.35% in urine and 3.05% in feces) of total radioactive quantity from the metabolite of [3,5-3H-Tyr]-Ser-Leu-OH were monitored. The distribution study revealed the relative accumulation level of the individual tissue was arranged in the sequence of spleen > liver > kidney > lung > heart > muscle > brain. Selecting hepatic cancer as the target YSL significantly increased the survival time of H22 tumor cells implanted mice.